The invention relates to motorcycle braking assemblies, and more particularly to brake rotor mounting assemblies.
It is known to use disc brakes on a motorcycle. Disc brake assemblies include a disc or rotor mounted to a wheel, and a caliper positioned next to the rotor and capable of clamping onto the rotor to slow down the rotation of the associated wheel. Known motorcycle disc brake assemblies fall roughly into two categories. The first category includes a rotor mounted at the hub of the wheel and a caliper clamping the radially outer edge of the rotor. This is the most common type of disc brake assembly used on existing cars and motorcycles.
The second category, a so-called xe2x80x9cinside-outxe2x80x9d assembly, includes a ring-shaped rotor mounted to the wheel along the rotor""s radially outer edge, and a caliper clamping the radially inner edge of the rotor. During braking, a rotor can become very hot due to the friction between the caliper and the rotor. It is known to mount inside-out rotors in a way that permits radial thermal expansion of the rotor during braking.
One known assembly for this purpose is disclosed in U.S. Pat. No. 4,716,993 (Bass), which teaches in FIGS. 8 and 9 an inside-out rotor having slots (60) in its outer edge. The rotor is mounted to a motorcycle""s wheel rim (16) with a spacer bush (64). The slots and spacer bush each have flat sides that are parallel to each other. According to the teachings of Bass, starting at column 4, line 66, xe2x80x9cAs the temperature of the discs begins to rise during braking, the disc will expand radially and said adjacent edge of the opening will slide along the flat of its bush.xe2x80x9d
The present invention involves the realization that disc brake rotors expand radially under thermal loads. Thus, a slot having parallel sides, such as taught by Bass, will widen as it thermally expands. Thermal expansion in the Bass assembly will therefore cause the sides of the slots to move away from the flats of the bush, which results in diminishing contact between the rotor and the bush during braking as the rotor is heated.
The present invention provides a motorcycle comprising a frame, a wheel mounted to the frame for rotation about an axis of rotation, a rotor mounted to the wheel, and a caliper selectively clamping the rotor to slow down the rotation of the wheel. The rotor includes a slot having flat sides that are non-parallel with respect to each other. The assembly further comprises a spacer positioned within the slot and having flat sides substantially parallel to the sides of the slot such that the flat sides of the spacer maintain contact with the flat sides of the slot during thermal expansion of the rotor.
Preferably, the rotor is ring-shaped and the brake assembly is an inside-out brake assembly. The spacer may be integrally formed with the wheel rim or may include a nut that is separable from the wheel. The assembly may further include a fastener that extends through the spacer and into the wheel, and that includes a head that prevents the rotor from moving away from the wheel. A spring is preferably provided between the rotor and the wheel and is offset from the fastener. The spring biases the rotor against the head of the fastener.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.